Method and apparatus for transferring liquid material



Get 17, 1933.- H. E. THoMPsdN METHOD AND APPARATUS FOR TRANSFERRINGLIQUID MATERIAL Filed Dec. 14. 19:52 2 sheets-sheer 1 I in u 'H iINVENTOR Oct. 17, 1933. H. E. THOMPSON HETHOD AND APPARATUS FORTRANSFERRING LIQUID MATERIAL Filed Dec. 14. 1952 2 Sheets-Sheet 2 VINVENTOR M (5 7 Man I Patented Oct. 17, 1933 UNITED STATES METHOD ANDAPPARATUS FOR TRANS- FERRING LIQUID MATERIAL Harold E.

Thompson,

Hastings on Hudson,

N. Y., assignor to, The Linde Air Products Company, New York, N. Y., acorporation of Ohio Application December 14, 1932 Serial No. 647,188

19 Claims.

This invention relates to a method and apparatus for transferring liquidmaterial, volatile at normal atmospheric pressure and temperature, andparticularly to liquefied gases which when under atmospheric pressurecan be stored in -the liquid phase only when their temperature is below273 K.

The invention has for its object generally the provision of an improvedmethod and apparatus for carrying out the same, whereby volatile liquidsof the character indicated are transferred from suitable containers to adevice or vessel adapted to receive the same, preferably in the gasphase, at a relatively high pressure.

More specifically, it is an object to provide a method and suitableapparatus by which a storage or transport container may hold liquefiedoxygen at a relatively low pressure and may transfer the same to areceiver by means of a 2D force-applying device such as a pump fordelivery at the desired high pressure, for example,

through a conduit which may include a vaporizing device whereby theoxygen is delivered in the gas'phase. It is also an object to provide amethod and apparatus for pumping liquids which are volatile at ordinaryatmospheric pressures and temperatures, in a manner which avoids havingthe pumping means become gas-bound, so that the pressure may be elevatedsubstantially to any desired value.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, and theapparatus embodying features of construction, combinations of elementsand arrangement of parts which are adapted to effect such 40 steps, allas exemplified in the following detailed disclosure, and the scope ofthe application of which will be indicated in the claims.

For a fuller understanding of the nature and 45 objects of theinvention, reference should be had to the following detailed descriptiontaken in connection with the accompanying drawings, in which:

Fig. 1 is a view partly in section and partly in elevation showingapparatus including a transport container adapted to supply a gasmaterial in the liquid phase and convert the same to the gas phase at adesired pressure, in accordance with the invention;

Fig. 2 is a view similar to Fig. 1 showing a modified form of apparatusconstructed in accordance with the invention;

Fig. 3 is a view mainly in section showing still another modificationadapted to achieve very high pressures; and

Fig. 4 is a fragmentary sectional view showing details of a pumpstructure suitable for use in the apparatus shown either in Figs. 1, 2or 3, the plane of the section being indicated by the line 44 in therespective figures.

Heretofore, when it was desired to transfer liquids which are volatileat normal atmospheric pressure and temperature to receiving devices orvessels, where the material received is maintained in the gas phase atrelatively high pressures, this was achieved by maintaining the volatilematerial under a sufilcient pressure to effect the desired transfer.-This had the result of requiring all parts including the supplycontainer to be built to resist great stress.

The alternative to this procedure involves generally the use of a forceapplying device, for example a pump, whereby the material may be drawnfrom the supply container by the suction of the pump and delivered atthe desired pressure. The use of a suction device, however, is notfeasible where the volatile material gasifies at ordinary atmosphericpressures and temperatures, since the suction device will not draw overgas material; for example, the suction stroke of a. pump under theseconditions merely causes the liquid in the clearance space to vaporize,this vapor being re-condensed during the delivery stroke of the pump.Under these circumstances, a pump is seen to accomplish no useful work90 and is said to be gas-bound.

In accordance with the present invention, volatile material whichvaporizes at normal atmospheric temperature and pressure, such as aliquefied gas, is delivered by forcing means from a supply source suchas a storage or transport container into a receiving device, where thematerial is maintained at the desired high-pressure without the forcingmeans becoming gas-bound. This is eifected by certain steps which effectthe desired elevation of pressure in a plurality of stages. Two stepsare preferably employed to raise the pressure, as desired, in acorresponding number of stages. In the first step, a pressure elevationis accomplished in conjunction with the liquid 105 to be transferredsuch that the pressure that is attendant the temperature environment nolonger permits the liquid being moved to flash into vapor under theinfluence of suction. This initial pressure elevation is, in general, arelatively 110 small part or fraction of the total pressure elevation tobe attained.

By the present invention, the pressure elevation of the first step isaccomplished in any one of several different ways. One way in which thisis accomplished is to apply temporarily an increase in pressure to thesupply body of volatile material, which in amount is suiiicient to avoidthe tendency to flash into vapor under the application of suctionwithout subjecting the parts, particularly the supply container, to thetotal stress involved in achieving the total pressure elevation desired.The pressure thus applied to the supply body of gas material mayconveniently be had by gasifying a small portion of the volatilematerial and applying the same to the surface of the supply body whileit is desired to transfer liquid from the container, the latter being ofa type adapted to be closed.

A second way in which this initial pressure elevation is accomplished isto provide an auxiliary source of pressure which may be temporarilyapplied to the surface of the supply body of volatile material while ina closed container. This is readily achieved in practice by providing anindependent vessel or cylinder containing gaseous material underrelatively high pressure and supplying the same during the period oftransfer to the surface of the volatile material in the storage ortransport container, or during the period that it is desired to withdrawvolatile material from the storage or transport container.-

Each of .the first and second ways of accom- V plishing this step ofinitially attaining a partial 35' elevation of the pressure to thedesired value, is particularly adapted for transport service, since thisstep may be attained with aprelatively small amount of apparatus, andhence may be provided on trucks for transporting storage containerswithout unduly weighting down the trucks.

A third way in which this initial pressure fraction is attained is bymeans of a pump so located that no suction is required to draw over thevolatile liquid, the flow being effected merely by means of the naturalforces operating in the system, for example by means of the force ofgravity. To this end, a pump is employed in the first stage of pressureelevation, preferably protected from the uncontrolled influence of heatfrom an external source, arranged to receive its supply of liquid underthe influence of the hydrostatic head of the system produced by gravity.In the second step of the process, one accomplishes a further elevationof the pressure, which gives finally the desired value and may force thevolatile material through a vaporizing means which supplies the volatilematerial in the gas phase at the desired high pressure. This second stepof pressure elevation is readily accomplished by pumping means arrangedto receive the material delivered under the fractional pressure elevation accomplished in the first stage, since liability of the gasmaterial to flash into vapor is now avoided. This second stage meansaccordingly may be a pump designed to deliver the volatile material atsubstantially any desired pressure.

Referring now to the drawings and particularly to Fig. 1, 10 denotesgenerally a container of the insulated variety adapted for transportservice and is mounted on the body of a truck denoted generally at 11.This container has an inner vessel 12 arranged to hold a liquid supplybody 13 of volatile material to be gasified, for example liquid oxygen.This container has a filling conduit 14 leading to the upper end of thevessel 12, the conduit having a gas-tight closure 15. A withdrawalconduit 16 leading preferably from the bottom of the vessel 12 has acontrol valve 17 and discharges into a small vaporizing means 18 thatcommunicates by way of conduit 19 with the upper end of the vessel 12above the normal liquid level of the body 13 held therein. Safety means20, such as a safety valve, is also provided to relieve the excessaccumulation of pressure which may arise within the vessel 12.

The small vaporizer 18 is of a capacity sufficient to vaporize aquantity of liquid material that will accomplish the fractional pressureelevation to be achieved in the first step of the method of the presentinvention. This vaporizer is controlled and receives its portion ofliquid from the vessel 12 by manipulating valve 17. The vaporizer shownis supplied withheat from any convenient source, for example, from theatmosphere at normal temperatures. Accordingly, the vaporizer 18 isinstalled on the truck in a manner such as to be readily exposed to acirculating body of atmospheric air. This is here shown as done byplacing the vaporizer 18 on the truck in a floor opening adjacent to thecontainer 10 arranged to have a draught of air passing therec' er.

When suflicient pressure has been generated and applied to the surfaceof the body 13 to prevent the same from flashing into vapor when beingdelivered to the second stage pressure elevating means, the forcingaction to accomplish the second stage pressure elevation ma be started.This is here achieved by providi g a suction conduit 21 leading from thevessel 12 to the suction side of a pump 22 that is also located on thetruck adjacent the transport container 10. A delivery conduit 23 leadsfrom the delivery side of the pump 22 and communicates with a highpressure vaporizer 24 that has sufficient capacity to gasify thevolatile material at a rate adapted to supply the demand and may bemounted on the truck 11. This vaporizer has a discharge conduit 25 fordelivering the volatile material in the gas phase at the desiredpressure. This may be either directly to a gas consuming apparatus or toa receiving vessel which holds the same temporarily in storage untilused, (such vessels being well known in the art, and are shown, forexample, in U. S. patent to Heylandt 1,786,159, the illustration thereofbeing omitted from the drawings in the interests of clearness).

The suction conduit 21 and the pump 22 which effects the second stagepressure elevation are preferably heat insulated, as indicated at 26, inorder to avoid heat leakage, which would otherwise operate to decreasethe eiiiciency of the system and to offset partially or wholly theadvantage of the partial pressure elevation accomplished in the firststage of the method of the present invention. A portion of the conduit21 may also with advantage be enlarged as indicated at 27 to provide asuction pot which operates to even the flow through the conduit 21 fromthe container 10 to the pump 22.

The pump 22 may be driven in any convenient manner, for example, bymeans of an electric motor 30, as shown in Fig. 4, which may be suppliedwith electric energy from any convenient source, for example from thelighting and ignition system of the truck 11. This motor is shown asmechanically coupled to drive a fiy-wheel 31 by means of a belt 32,which fly-wheel drives a crank 33 that is coupled to the piston rod 34of the pump by a connecting rod 35 and cross-head 36. The piston rod 34is shown as passing through a packing gland 37 and provided with apiston 38 which is adapted to reciprocate in the cylinder 39, here shownas double acting. The suction chamber of the pump is here shown on thelower side at 40 and has communication with the cylinder 39 throughinwardly opening valves 41, here indicated as of the poppet variety. The

discharge chamber is similarly shown on the upper side of the pump at 42and communicating with the ends of the cylinder through outwardlyopening valves 43, also indicated as of the poppet variety. The suctionconduit 21 leads directly to the suction chamber 40, while the dischargeconduit 23 leads from the discharge chamber 42, the whole pump beingencased in heat insulation, indicated generally at 46, which may beregarded as an extension of the heat insulation already referred to andshown at 26.

By this means, it is seen that the second stage pressure elevation isaccomplished as follows: When the pump piston 38 is displaced, forexample to the right, the poppet valve 41 on the left opens to admitliquid to fill the space made vacant by piston displacement. This liquidflows through the suction conduit 21 under the influence of the partialpressure elevation effected in the first stage and applied to thesurface of the liquid in the container 10, so that flow is accomplishedwithout liability of the liquid flashing into vapor. The pistondisplacement toward the right is at the same time accompanied by anopening of the poppet valve 43 on the right to admit liquid to thedelivery chamber 42 and force the same under a head of pressure to fiowout through the conduit 23 into the vaporizer 24. When the pistondisplacement toward the right is completed, a stroke toward the left isbegun. The displacement effected during such stroke causes the poppetvalve 41 on the left to close and the poppet valve 41 on the right toopen, this opening and closing of the valves 41 being accompaniedsubstantially at the same time as the closing of the poppet valve 43 onthe right and the opening of a poppet valve'43 on the left, whereby theliquid just drawn into the cylinder 39 by the piston displacement fromleft to right is now forced out through the poppet valve 43 on the leftinto the discharge chamber 42, thereby continuing the pumped supply ofvolatile liquid to the vaporizer 24 as long as the partial pressureelevation accomplished in the first stage is maintained.

In Fig. 2 an arrangement of apparatus is shown adapted for effecting theinitial partial pressure elevation in the second way described above.Here a transport container denoted generally at 10 is mounted on a truckbody 110 and is provided with an inner vessel 12 adapted to hold a bodyof volatile liquid insulated from the thermal environment of theatmosphere similar to the arrangement shown in Fig. l. The vessel 12 isalso shown as provided with a filling'connection 14 and a closure 15.The container is also provided with a withdrawal conduit 210 leading tothe suction side of a pump 22 that has a discharge conduit 23 leading toa vaporizer 24. The withdrawal conduit is preferably controlled by avalve 170.

In this arrangement, the initial pressure fraction is supplied by meansof compressed gas from an auxiliary vessel 48 through a conduit 49leading to the vessel 12 and entering the same above the normal liquidlevel therein. The'gas thus supplied should be without chemical airlnityfor the liquid material within the vessel 12 in order to avoidcontaminating or disturbing the equilibrium of the latter. Where theliquid material in the vessel 12 is, for example, liquid oxygen, thecompressed gas in the auxiliary reservoir 48 would preferably be oxygenin the gas phase compressed to several atmospheres. A safety valve isalso preferably employed, as indicated at 50, in order to avoid theundue accumulation of pressure within the container 10. In otherrespects, the system of Fig. 2 is like that shown in Fig. 1 and operatessimilarly.

An arrangement for accomplishing the initial partial pressure elevationhere desired, in accordance with the third way described above, isillustrated in Fig. 3. Here, a storage container 100 of the insulatedvariety has an inner vessel 12 for holding a body 13 of volatilematerial and has a filling connection 14 provided with a closure 15. Awithdrawal conduit 51 is provided leading from the bottom of the vessel12 to the suction side of a first stage pump 221. This conduit ispreferably provided with a suction pot, as indicated at 270, the wholebeing arranged to permit the flow of fluid into the pump cylinder underthe influence of the mechanical forces operating in the system. Here,the flow is caused by the hydrostatic head of the body 13. The firststage pump 221 has a discharge conduit 231 leading to an inter-stagecapacity chamber 52, from which the suction conduit 53 leads to a secondstage pump 222. A discharge conduit 232 leads from the discharge side ofthe pump 222 to supply the volatile material now elevated to the desiredpressure to a suitable receiving device, such as a high pressurevaporizer (not shown in the interests of clearness) Where the forcingmeans of the second stage is a pump of the reciprocating varietydelivering volatile material at a relatively high pressure, there is,unless suitable precautions are taken, a surge transmitted in the bodyof the volatile material being delivered. Such a surge effect issometimes referred to as a water hammer. The precautions to be taken toavoid this effect involve, in general, the use of surge suppressingmeans adapted to react against the surge in substantially a dead beatmanner. This is readily accomplished by means of a surge chamberconnected to the high pressure delivery conduit and containingcompressed gas which when momentarily further compressed by the surgereacts to apply compensating pressure.

Where the volatile material being pumped is a liquefied gas of lowboiling point, such as liquid air, liquid oxygen, or the like, the bodyof gas in the surge chamber is liable to be condensed by therefrigerating effect of the liquefied gas being delivered. According tothe practice of the present invention, means are provided in conjunctionwith the surge chamber for maintaining the compensating pressuresubstantially constant without liability of diminution throughcondensation. To this end, an auxiliary chamber is arranged to havecommunication with the surge chamber and receive a portion of the gaswhich is heated to compensate for the refrigerating effect. In thismanner, a desired gas pressure is maintained in the surge chamberwithout likelihood of contamination of the gas material being delivered.

Any surges engendered in the conduit 232 as a result of the periodicimpulses impressed by the pump 222 are suppressed by means of a surgechamber 54 which communicates with the discharge conduit 232 at anysuitable point, for example, one in proximity to the pump 222,as-indicated in the drawings. This surge chamber, as well as thedischarge pipe lines, are also preferably highly insulated. A second orauxiliary chamber is connected to the first chamber by a connection 56,the second chamber receiving a supply of inert gas from an externalsource, for example, from a cylinder of compressed gas, as shown at 57,connected by a conduit 58 with the top of the second chamber.Condensation of gas in this chamber is avoided by means of heat, whichis applied through a coil 59, disposed about the chamber 55 and has asuitable heating agent coursing therethrough.

In this last arrangement, the first stage pump effects the initialpressure elevation to the desired fractional value of the final pressureand discharges the material at such pressure into the chamber 52, fromwhich it is drawn by the second stage pump 222 and finally elevated bythe second pump to the desired high pressure. The liquid material in thechamber 52 is thus under a pressure such that when sucked up into thesuction chamber of the second stage pump 222, there is no liability ofthe liquid material to flash into vapor. While the liquid material thuspassed into the chamber 52 is desirably always under pressure, a toohigh pressure is to be avoided. Accordingly, a relief valve is shown at60 adapted to afford relief for the chamber 52 in case there is anexcess accumulation of pressure within the inter-stage chamber.

In order that the desired pressure fraction may be maintained in chamber52, both pumps are arranged to deliver liquid at the same rate. This maybe accomplished in any convenient manner, for example, by providing thatthe pumps, with equal volumetric displacements, shall be driven atspeeds that remain substantially constant. To compensate for anyinequalities in the delivery rates of pumps 221 and 222, it may bedesirable, though it is by no means necessary, to have the first stagepump made to pump at a slightly greater rate than the second stage pumpand the excess gas material delivered permitted to discharge from therelief valve 60.

' This may be returned by way of a conduit which conducts the same tothe suction side of the first stage pump or to the storage vessel 12.The loss of valuable gas material is thus avoided while the partialpressure is maintained.

Since certain changes in carrying out the above process and in theconstructions set forth, which embody the invention, may be made withoutdeparting from its scope, it is intended that all matter contained inthe above description or shown in the accompanying drawings, shall beinterpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is:

l. The method of transferring liquid material, volatile at normalatmospheric pressure and temperature, from a source of supply at arelatively low pressure to a receiver at a relatively high pressure,which comprises causing a flow of liquid from said source to saidreceiver, and during said flow elevating the pressure to he desiredvalue in a plurality of stages, in the first of which an intermediatepressure is attained sufficient to avoid flashing into vapor undersuction and in the remainder of the stages attaining the desiredpressure value compressibly.

2. The method of transferring liquid material,

volatile at normal atmospheric pressure and temperature, from a sourceof supply at a relatively low pressure to a receiver at a relativelyhigh pressure, which comprises causing a flow of liquid from said sourceto said receiver, and during said flow elevating the pressure to thedesired value in two stages, in the first of which an intermediatepressure is attained sufiicient to avoid flashing into vapor undersuction, and in the second attaining the desired value by applying forcecompressibly to the flowing liquid.

3. The method of transferring liquid material, volatile at normalatmospheric pressure and temperature, from a source of supply at arelatively low pressure to a receiver at a relatively high pressure,which comprises causing a flow of liquid from said source to saidreceiver, and during said fiow elevating the pressureto the desiredvalue in two stages, in the first of which an intermediate pressure isattained sufiicient to avoid flashing into vapor under suction byutilizing the natural forces operating in the system, and in the secondstage attaining the desired pressure value by pumping the flowing liquidagainst a head of pressure.

4. The method of transferring liquid material, volatile at normalatmospheric pressure and temperature, to be supplied at a desired highpressure, which comprises charging a heat insulated container with asupply body of liquid material having a pressure environment notsubstantially different from that of the atmosphere, withdrawing liquidfrom said container under natural forces operating in the system to afirst stage pressure elevating means whereby an intermediate pressureelevation is achieved sufficient to prevent flashing into vapor whendelivered to a subsequent stage, and thereafter in a second stageforcing the liquid up to a desired higher pressure by means of anexternally operated pump. 11

5. The method of transferring liquid material, volatile at normalatmospheric pressure and temperature, to be supplied at a desired highpressure, which comprises charging a heat insulated container with asupply body of liquid material having a relatively low pressureenvironment, withdrawing liquid from said container under natural forcesoperating in the system to a first stage pump externally operated,effecting a partial pressure elevation by means of a pump to a valuesufiicient to prevent flashing when delivered to a second stage pump,and thereafter effecting a pressure elevation by said second stage pumpsufficient to achieve a desired higher pressure.

6. The method of transferring liquid material, volatile atnormalatmospheric pressure and temperature, to be withdrawn from a supply bodyand transferred to a receiver at a desired high pressure, whichcomprises causing a flow of liquid material from said supply body havinga pressure environment not substantially different from that of oneatmosphere, introducing liquid from said body under natural forcesoperating in the system to a first stage pump externally operated,effecting a pressure elevation by said first stage pump less than saiddesired high value but sufiicient to prevent flashing when delivered toa second stage pump, then eifecting a pressure elevation to the desiredvalue by said second stage pump, and suppressing surges in the deliveryof the medium from said second stage pump.

7. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, delivery means connected to said container.means for effecting a partial elevation of the pressure in the materialdelivered to a desired intermediate value, and forcing means arranged toreceive said liquid material delivered at the partial pressure andeffect a further pressure elevation to a desired value.

8. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, delivery means connected to said container,means for effecting a partial elevation of the pressure in the materialdelivered to a desired intermediate value, and a pump arranged toreceive said liquid material at said partial pressure and to deliver thesame at a pressure of the desired value.

9. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, delivery means connected to said container,means for effecting a partial elevation of the pressure in the materialdelivered to a desired value, pumping means arranged to receive theliquid material at said partial pressure and to deliver the same with afurther elevation of the pressure, and a high pressure vaporizing meansarranged to receive the material delivered by said pumping means and todeliver the same in the gas phase at the desired high pressure.

10. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, delivery means connected to said container,means for effecting a partial elevation of the pressure in the materialdelivered to a desired intermediate value, delivery means leading fromsaid partial pressure elevating means having an enlargement, and areciprocating pump having a suction conduit leading from saidenlargement and a delivery conduit leading to a receiving device; saidpump being arranged to effect a further pressure elevation whereby thematerial is finally delivered at the desired pressure.

11. Apparatus for transporting and delivering a liquefied gas, volatileat normal atmospheric pressure and temperature, comprising a transportvehicle, a container of the insulated type mounted on said vehicle,delivery means connected to said container, additional means on saidvehicle for effecting a partial elevation in the pressure of thematerial in said delivery means to a desired value, pumping means onsaid vehicle arranged to receive said material at said partial pressureelevation and to effect a further pressure elevation, and vaporizingmeans arranged to receive said material from said pumping means and todischarge the same in the gas phase at a desired high pressure.

12. Apparatus for transporting and delivering a liquefied gas, volatileat normal atmospheric pressure and temperature, comprising a transportvehicle, a container of the insulated type mounted on said vehicle,delivery means connected to said container, additional means on saidvehicle for effecting a partial elevation in the pressure of thematerial in said delivery means to a desired value, a reciprocating pumpon said vehicle having its suction side connected to said delivery meansand adapted to receive said material at said partial pressure elevation,a second delivery means leading from the discharge side of said pump,and a-high pressure vaporizer on said vehicle connected to receive thematerial from said second delivery means and to discharge the same inthe gas phase at adesired high pressure.

13. Apparatus for transporting and delivering a liquefied gas, volatileat normal atmospheric pressure and temperature, comprising a transportvehicle, a container of the insulated type mounted on said vehicle,delivery means connected to said container, additional means on saidvehicle for effecting a partial elevation in the pressure of thematerial in said delivery means to a desired value, a reciprocating pumpon said vehicle having its suction side connected to said delivery meansand adapted to receive said material at said partial pressure elevation,a second delivery means leading from the discharge side of said pump,power means associated with the power plant of said vehicle forpropelling said pump, and a high pressure vaporizer on said vehicleconnected to receive the material from said second delivery means and todischarge the same at a desired high pressure to a receiving device.

14. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, a delivery conduit leading from said containerin which flow is effected under the influence of natural forces, a firststage pump having its suction side connected to said conduit, a seconddelivery conduit leading from the discharge side of said first stagepump, a. second stage pump having its suction side connected to saidsecond delivery conduit, and a third delivery conduit adapted to leadthe discharge from the second stage pump to a receiving device.

15. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, a delivery conduit leading from said containerin which flow is effected under the influence of natural forces, a firststage pump having its suction side connected to said conduit, a seconddelivery conduit leading from the discharge side of said first stagepump, an inter-stage enlargement in said second delivery conduit, asecond stage pump having its suction side communicating with saidenlargement, and a third delivery conduit leading the discharge fromsaid second stage pump to a receiving device. I

16. Apparatus for transferring liquid material, volatile at normalatmospheric presssure and temperature,comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, a delivery conduit leading from said containerin which flow is eifected under the influence of natural forces, a firststage pump having its suction side connected to said conduit, a seconddelivery conduit leading from the discharge side of said first stagepump, said first stage pump applying a partial pressure elevation to thematerial being delivered sufficient to avoid having the same flash intovapor under the influence of suction, a second stage pump having itssuction side connected to receive said liquid material under said'partial pressure elevation and arranged to ,deliver the same at afurther pressure elevation to a desired value, and means for insuringthe delivery of material from said pumps at substantially the same rate.

17. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, a delivery conduit leading from said containerin which flow is effected under the influence of natural forces, a firststage pump having its suction side connected to said conduit, a seconddelivery conduit leading from the discharge side of said first stagepump, said first stage pump applying a partial pressure elevation to thematerial being delivered sufficient to avoid having the same flash intovapor under the influence of suction, a second stage pump having itssuction side connected to receive said liquid material under saidpartial pressure elevation and arranged to deliver the same at a furtherpressure elevation to a desired value, a third delivery conduit leadingthe discharge from said second stage pump to a receiving device, and asurge suppressing device connected to said third delivery conduit; saiddevice including means for avoiding diminution of pressure thereinthrough condensation.

18. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid ma verial adapted to be held normally at arelatively low pressure, a delivery conduit leading from said containerin which fiow is eiiected under the influence of natural forces, a firststage pump having its suction side connected to said conduit, a seconddelivery conduit leading from the discharge side of said first stagepump, said first stage pump applying a partial pressure elevation to thematerial being delivered suflicient to avoid having the same flash intovapor under the influence of suction, a second stage pump having itssuction side connected to receive said liquid material under saidpartial pressure elevation and arranged to deliver the same at aiurtherpressure elevation to a desired value, an interstage enlargement in theconduit leading from said first stage pump to said second stage pump,and means associated therewith for insuring the delivery of materialfrom said pumps at substantially the same rate.

19. Apparatus for transferring liquid material, volatile at normalatmospheric pressure and temperature, comprising a container for asupply body of said liquid material adapted to be held normally at arelatively low pressure, a delivery conduit leading from said containerin which flow is effected under the influence of natural forces, a firststage pump having its suction side connected to said conduit, a seconddelivery conduit leading from the discharge side of said first stagepump, said first stage pump applying a partial pressure elevation to thematerial being delivered sufficient to avoid having the same flash intovapor under the influence of suction, a second stage pump having itssuction side connected to receive said liquid material under saidpartial pressure elevation and arranged to deliver the same at a furtherpressure elevation to a desired value, an interstage enlargement in theconduit leading from said first stage pump to said second stage pump,means associated with said enlargement for insuring the delivery ofmaterial from said pumps at substantially the same rate, a thirddelivery conduit leading the discharge from said second stage pump to areceiving device, and a surge suppressing device connected to said thirddelivery conduit including means for preventing gas condensation thereinby .the refrigerating effect of the material being delivered.

HAROLD E. THOMPSON.

